The present invention relates to crop harvesting machines for mowing a standing crop and for bruising the stems of the crop by feeding it between conditioner rolls or into engagement with a conditioning rotor, these machines being commonly called mower-conditioners (hereinafter often referred to as mocos); and, more particularly, the present invention relates to a drive system for such a machine.
The drive system for conveying power on a moco will vary with the type of moco. Specifically, a sickle moco, i.e., one that uses a sickle type cutterbar for severing crop from the ground, can have four powered elements, namely, a wobble box of the cutterbar, a reel, an upper conditioner roll and a lower conditioner roll. A rotary moco, i.e., one that uses a rotary disc type cutterbar for severing crop from the ground will either have two or three powered elements, e.g., a drive box of the cutterbar and an impeller conditioner, or a drive box of the cutterbar, an upper conditioner roll and a lower conditioner roll.
The upper and lower conditioner rolls of known mocos are usually driven by a gear train enclosed in a large, oil-containing gearbox and having counter-rotating output shafts respectively coupled to the upper and lower conditioner rolls by means of u-joint drive lines, the drive line to the upper conditioner roll being necessitated by the fact that the upper conditioner roll is mounted for moving vertically to accommodate varying crop volumes passing between the rolls. Although these drive lines are kept as short as possible, they increase the overall width of the machine. The drive lines also add cost and complexity to the machine and require periodic lubrication.
Impeller conditioners have a single powered rotor. It is common to provide the operator a choice of two rotor speeds to accommodate different crop types. This is done by transposing the driver and driven sheaves which have different diameters. This requires the drive speed to be mid-range of the two rotor speeds.
Two standard tractor power take-off speeds are available, these being 540 and 1000 rpm. Although 540 rpm is the most popular speed, 1000 rpm is preferred on high-powered implements such as rotary mocos. Traditionally, mocos are manufactured for a single PTO speed and can't be economically converted at the point of sale to the other speed. This causes increased inventory at the factory and adds an impediment to the sale.
An adjustable slip clutch is usually used in the main drive to prevent drive component damage due to high power consumption or lock-up. Because the clutch is usually a separate assembly which is not combined with other drive components, it adds cost to the mocos. Also, the slip clutch settings for 540 and 1000 rpm are not the same even though the moco may be the same. This causes user confusion and incorrect adjustment.